1. Field of the Invention
The present invention generally relates to Wideband Code Division Multiple Access (W-CDMA) and, more particularly, to an address generation apparatus for turbo interleavers and deinterleavers in W-CDMA systems.
2. Background of the Invention
Turbo codes are widely used in digital data transmission because of their high coding gain. A Turbo code is a built from a concatenation of two Recursive Systematic Convolutional (RSC) codes, linked together by an internal interleaver.
The internal interleaver is an important component in a Turbo encoder and greatly affects the performance of the Turbo code. Typically, a turbo interleaver is a block-type interleaver with inter-row permutation, intra-row permutation and pruning. However, other types of interleavers may be used for turbo codes including, for example, random interleavers. In a block interleaver, the data are read in by rows and form a matrix, with certain paddings if the data does not fill up the matrix. After permutations are performed within rows and among rows, the data are read out in columns with pruning of the paddings. A random interleaver rearranges the data using a randomly generated permutation pattern.
Commonly, interleavers/deinterleavers are implemented by using a memory device to store the address pattern of the interleavers/deinterleavers. However, in W-CDMA systems, the length of a Turbo code block can vary from 40 bits to 5114 bits. Hence, 5075 different address patterns need to be stored in the memory device, resulting in the need for a significantly large memory device that may not be practical.
Accordingly, it would be desirable and highly advantageous to have an address generation apparatus for turbo interleavers and deinterleavers that overcomes the above-identified deficiencies of the prior art.